DTU Physics, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark.
Nanoscale. 2019 Mar 28;11(13):6153-6164. doi: 10.1039/c9nr00866g.
Multi-scale computational approaches are important for studies of novel, low-dimensional electronic devices since they are able to capture the different length-scales involved in the device operation, and at the same time describe critical parts such as surfaces, defects, interfaces, gates, and applied bias, on a atomistic, quantum-chemical level. Here we present a multi-scale method which enables calculations of electronic currents in two-dimensional devices larger than 100 nm2, where multiple perturbed regions described by density functional theory (DFT) are embedded into an extended unperturbed region described by a DFT-parametrized tight-binding model. We explain the details of the method, provide examples, and point out the main challenges regarding its practical implementation. Finally we apply it to study current propagation in pristine, defected and nanoporous graphene devices, injected by chemically accurate contacts simulating scanning tunneling microscopy probes.
多尺度计算方法对于研究新型低维电子器件非常重要，因为它们能够捕捉到器件工作中涉及的不同长度尺度，同时在原子、量子化学水平上描述表面、缺陷、界面、栅极和外加偏压等关键部分。在这里，我们提出了一种多尺度方法，能够计算大于 100nm²的二维器件中的电子电流，其中多个由密度泛函理论（DFT）描述的扰动向一个由 DFT 参数化紧束缚模型描述的扩展无扰区中嵌入。我们解释了该方法的细节，提供了示例，并指出了其实际实现的主要挑战。最后，我们将其应用于研究由化学精确接触模拟扫描隧道显微镜探针注入的原始、有缺陷和多孔石墨烯器件中的电流传输。
